Prefabs and collisions

Hello,

Here is my situation. When i collide with a power up, it will fire an 'egg' to an object to remove it. The egg is a prefab and so is the object. I have given the egg a tag so when it collides with the object, the object will realise that the egg has just collided with it and needs to delete itself.

Yet it does not want to work. It is making me believe that there is something very odd with working with prefabs. Yet i would like them. I have done this type of code in javascript before where i find a gameobject with a specific tag, so i know its not the codes problem. Was just wondering if there is a specifc thing i should know when working with prefabs and tags.